1. Field of the Invention
The present invention is directed to removable scratch-off coatings and items that incorporate scratch-off coatings to obscure images from view. More particularly, the present invention is directed to the use of laser technology to sublimate images beneath the scratch-off coatings.
2. Background
Many instant-win lottery cards are coated in one or more regions by scratch-off coating compositions in order to hide symbols that comprise game indicia. When a purchaser of such a card scratches off the coating, he or she reveals the symbols and learns the results of the game. Instant-win tickets, phone cards, promotional labels and other games similarly incorporate scratch-off coatings to hide various symbols.
Instant-win lottery cards, like other games that incorporate scratch-off coatings, typically are layered with a complex array of coatings of varying compositions. The complex construction provides a card that is both durable and relatively secure from tampering. U.S. patent application Ser. No. 08/407,185 now U.S. Pat. No. 5,569,512 (which application is hereby incorporated by reference herein) discloses several arrays of coatings that a card can incorporate.
The substrate, or base, of many instant-win lottery cards is cut from cellulosic board stock. A metallic foil is then laminated to the board stock. The metallic foil is coated with a primer to minimize oxidation and to provide a surface that is receptive to ink. After symbols have been printed atop the primer in pigmented ink, a sealant is frequently applied over them to protect the printed symbols. A scratch-off coating, which typically is comprised of an opaque metallic latex, is applied over the printed symbols and sealant to obscure the symbols from view. To facilitate removal of the scratch-off coating from the card, existing cards often further include at least one "release" coat interposed between the scratch-off coating and ink sealant.
In addition to providing a durable substrate for the production of instant-win cards, a cellulosic board stock and foil combination provides a level of opacity and impermeability that is important to the security of the card. The board stock and foil combination inhibits unscrupulous players from viewing the printed symbols by examining the ticket before a light source, a process known as candling. The non-porous foil also protects the card from chemical tampering by preventing unscrupulous players from chemically wicking the hidden symbols to the underside of the substrate where they might become visible.
While existing foil-based cards may be durable and secure, they are difficult and expensive to manufacture because they are constructed of numerous coatings and layers. Many times these coatings and layers are comprised of specialty chemicals to ensure that the layers are compatible with and adhere to one another. These specialty chemicals are often very expensive. The foil in foil-based cards is another significant raw material expense, and it adds an element of complexity to the manufacturing process. Foil-based cards also are difficult to recycle because the metal foil interferes with conventional paper recycling processes. The foil further prevents electrostatic printing techniques from being employed, reducing the variety of graphics available for use. The use of ink to print the symbols is also problematic. Ink printing requires that two additional processing steps be incorporated into the card manufacturing process, one printing step and another sealant step. Each of these steps substantially increases the time and expense required to manufacture existing cards.
An instant-win card that is different from those discussed above was recently introduced. This card appears to omit foil from its base, and instead to incorporate a water-based black coating over the conventional board stock. The black coating is approximately one micron thick and comprised of carbon, chlorine, and calcium. This black coating is believed to be either identical or virtually identical visually to the composition of the ink used to print the hidden images on the card thus diminishing the possibility that an unscrupulous player could distinguish the hidden images from the coating through candling. To contrast the hidden images from the black base coating, and to receive more readily printed symbols, the card interposes a lighter color coating between them. This card however, like others discussed above, is complex.